1. Technical Field
The present invention relates to a liquid container which contains liquid to be supplied to a liquid ejecting apparatus.
2. Related Art
In the past, as a system of a liquid container which contains liquid to be supplied to a liquid ejecting apparatus, there has been a semi-hermetically-sealed type. In a semi-hermetically-sealed type liquid container, at least a portion of a liquid containing space is constituted by a member having flexibility, for example, a sheet. The sheet is deformed in accordance with the consumption of liquid, so that the liquid containing space is reduced. Then, the inside of the liquid containing space is maintained at negative pressure by a spring which pushes up the flexible sheet against contraction. As a result, when the liquid ejecting apparatus does not consume liquid, liquid does not flow out from the liquid container to the liquid ejecting apparatus side.
At the semi-hermetically-sealed type liquid container, an air inlet for introducing air into the liquid containing space is provided. Then, at a point in time when the sheet is deformed, whereby the liquid containing space is reduced to some extent, a valve of the air inlet is opened, so that air is introduced into the liquid containing space. As a result, the liquid containing space slightly increases by the amount of introduced air. At the same time, the negative pressure in the liquid containing space slightly decreases (becomes closer to atmospheric pressure). Thereafter, in the semi-hermetically-sealed type liquid container, a movement is repeated in which in accordance with consumption of liquid, negative pressure is increased by the spring which pushes up the flexible sheet and every time the air inlet is opened, the negative pressure is slightly decreased (becomes closer to atmospheric pressure). As a result, a negative pressure stable within a certain range can be realized until the use of the liquid container is ended, except for a time immediately after the start of use of the liquid container. As a result, the amount of unused liquid remaining in the liquid container also becomes small compared to a hermetically-sealed type.
For example, in an ink containing container of Japanese Patent No. 4144842, a movable member 11 as a sheet having a planar shape of a rectangle is attached at four sides thereof to a frame 18 which forms a rectangular ring. Further, a planar plate 14 is attached to the movable member 11. Then, the planar plate 14 is displaced with respect to the frame 18 with the deformation of the movable member 11 which is a sheet. A spring 43 provided in a storage space supports the planar plate 14 at one point and pushes up the planar plate 14 along with the movable member 11 which is a sheet. On the other hand, when the negative pressure of the storage space has increased to be equal to or more than a predetermined value, outside air is introduced through a ventilation portion 1. In the technology of Japanese Patent No. 4144842, a function as the above-described semi-hermetically-sealed type liquid container is realized by these operations.
JP-A-2003-191488 and JP-A-2003-251826 are other examples of the related art.
However, in the technology of Japanese Patent No. 4144842, the planar plate 14 is supported at the outer circumference thereof on the movable member 11 which is a sheet, and further pressed by the spring 43 at one point. For this reason, at the time of displacement accompanying a reduction in ink, the planar plate 14 is not displaced with a constant position always maintained with respect to the frame 18, but can be displaced with it inclined in various positions. For this reason, in a case where the liquid container is provided with a mechanism which performs a given operation on the basis, for example, of the position of the planar plate 14, the operation of the mechanism is not stable.
Also, since the planar plate 14 can be displaced with it inclined in various positions, the shape of the storage space can be variously changed in the above-mentioned operation of repeating an increase in negative pressure and introduction of outside air. For this reason, the liquid level of ink in the storage space does not also maintain the tendency of a reduction within a certain variation range, but largely increases or decreases in accordance with the position of the planar plate 14. Accordingly, in a case where the liquid container is provided with a mechanism which performs a given operation on the basis, for example, of the position of the liquid level of ink, the operation of the mechanism is not stable.
That is, in the technology of Japanese Patent No. 4144842, since the planar plate 14 can take various positions in the liquid container, in a case where the liquid container is provided with a mechanism which performs a given operation on the basis of the state of the inside of the liquid container, the operation thereof is not stable. Such a problem does not occur only in the liquid storage container, but widely occurs in a semi-hermetically-sealed liquid container in which a change in volume is induced by deforming a member having flexibility.